There currently exists cameras that have the capability of providing more than one size format image for a single filmstrip. For example, the Kodak Cameo camera can take either standard or panoramic format size pictures as desired (often referred to as interspersed pan feature).
In order for high speed photographic printers to print developed film obtained from cameras capable of taking two or more format size images, the paper exposure zoom lens assembly on the printer must be capable of switching back and forth between magnifications for different print formats. To achieve or maintain high productivity, the lens assembly of an electromechanical drive system of a zoom lens assembly must be capable of performing at high speed and accelerations without incurring mechanical binding or excessive component wear. It is expected that a zoom lens assembly in a high volume photofinishing operation may experience upwards of 80 million actuations.
Typical lens assembly designs for high speed printers utilize cam and follower drive designs which are not particularly suited for high speed operation or extensive repetitive change. Cam and follower drives are expensive and susceptible to wear-related component failures.
Typical electromechanical lead screw drive systems are mechanically over-constrained, requiring expensive motor couplings and precise machining and alignments.
Other mechanical arrangements also suffer from the same deficiencies as cam and follower assemblies. Gears and belts are not suitable for high actuations in that they either wear out too quickly or are subject to frequent replacement.
It is highly desirable to provide an exactly constrained and accurate zoom lens assembly that is of low cost to manufacture, easy to assemble, and also is capable of long extended use for millions of actuations without component failure or maintenance.